This paper describes a new radiator core design concept that may be used to replace the conventional multi-row “tube and center” design. It offers several mechanical and thermal design advantages for copper-brass radiators. Conventional multi-row radiator cores must be made with a space between the tubes in the air flow direction. This is required to obtain a sufficient ligament in the header. This space between the tube rows causes a loss of the potential thermal performance. The new concept described alleviates the need for a space between the tube rows. The design allows for zero space between the tube rows. This will provide excellent heat conduction from the tubes to the fin over the full fin depth in the air flow direction. Further, it will allow louvering of the fins over the full fin depth, which will also contribute to higher thermal performance. The tube ends are reshaped to a larger minor radius. This should provide crack-free headers, and result in greater radiator durability. The larger tube end radius will result in reduced stress on the tube-header joint. Practical limitations exist on the minimum required transverse tube pitch, Pt,min. Other design limitations on Pt,min (e.g., fin compressive strength and fin efficiency) are also addressed.